1. Field of the Invention
The present invention relates to a variable valve apparatus of an internal combustion engine capable of changing a phase or amount of lift of a intake valve or an exhaust valve.
2. Description of the Related Art
A reciprocating engine mounted in an automobile as an example of an internal combustion engine is provided with a variable valve apparatus, which changes the phases or the open/close timing of a intake valve and an exhaust valve, and the amount of lift of the valves, in order to reduce exhaust gas and to enhance fuel efficiency of the engine.
Many of such variable valve apparatuses have a structure to change the characteristics of a intake valve and an exhaust valve by replacing the phase of a cam formed in a camshaft by a rocking-reciprocating cam comprising a continuous base circle section and a lift section.
Recent valve apparatuses have a structure such that a control arm is supported by a rotatable control shaft, and a transmission arm contacting a cam is supported at an end portion of the control arm, in order to reduce a pumping loss. In this structure, when a control shaft is rotated, a transmission arm is moved, which changes the position at which the cam and transmission arm come into contact. Thus, phases of a intake valve and an exhaust valve are changed, especially largely changed in a valve-closed period compared with a valve-opened period (refer to Jpn. Pat. Appln. KOKAI Publication No. 2003-239712, for example).